1. Field of the Invention
The present invention relates to an X-ray diagnostic apparatus which copes with contrast study of a heart or the like.
2. Description of the Related Art
In X-ray contrast study of hearts and intervention, it is very important to understand shapes and functions of blood vessels and hearts. However, since cardiac movement cannot be avoided differently from the other regions of bodies, projection data is mainly used for the understanding of the hearts.
In recent years, applications for heart regions are gradually being developed. They include an application for creating a digital subtraction angio (DSA) image of coronary artery, an application for identifying perfusion from coronary artery to cardiac muscle, an application for locally/wholly creating a three-dimensional structure of coronary artery, and the like.
In order to create a DSA image of coronary artery, an image which hardly has an effect of a contrast agent is required as a satisfactory mask image for at least one heart rate. In some cases, the timing at which injection of contrast agent starts is too early and thus satisfactory mask images for one heart rate cannot be collected. This becomes a fatal problem for the creation of DSA images. Also when the perfusion from coronary artery to cardiac muscle is identified, the similar problem might arises.
When a three-dimensional structure of coronary artery is locally or wholly created, an image at end-diastole with comparatively less movement becomes a key. For example, in a method for paying an attention only to a target region and correcting a movement of this region so as to create a local three-dimensional structure, a target region is specified on an image at end-diastole.
When photographing is started just after the end-diastole passes, the number of end-diastoles to be included in an any photographing zone might be reduced. Since the amount of specifying information is reduced in this case, information is insufficient, and thus restructure is at risk of being unsatisfactory.
On the other hand, when a three-dimensional structure of coronary artery is wholly created, the restructure is carried out by using only images at end-diastole and less information. In such a method, image quality is greatly influenced by whether the number of end-diastoles is reduced by one or increased by one.